On 04/16/2018 11:34 AM, Pavel Stehule wrote: > Hi, > > my customer does performance checks of PostgreSQL 9.5 and 10. Almost all > queries on 10 are faster, but there are few queries (40 from 1000) where > PostgreSQL 9.5 is significantly faster than. Unfortunately - pretty fast > queries (about 20ms) are too slow now (5 sec). > > attached execution plans > > It looks like some cost issue, slow queries prefers Seq scan against > bitmap heap scan > > Hash Cond: (f_ticketupdate_aad5jtwal0ayaax.dt_event_id = > dwh_dm_aabv5kk9rxac4lz_aaonw7nchsan2n1_aad8xhr0m_aaewg8j61ia.id > <http://dwh_dm_aabv5kk9rxac4lz_aaonw7nchsan2n1_aad8xhr0m_aaewg8j61ia.id>) > -> Parallel Seq Scan on f_ticketupdate_aad5jtwal0ayaax > (cost=0.00..1185867.47 rows=24054847 width=8) (actual > time=0.020..3741.409 rows=19243863 loops=3) > -> Hash (cost=27.35..27.35 rows=7 width=4) (actual > time=0.089..0.089 rows=7 loops=3) > Buckets: 1024 Batches: 1 Memory Usage: 9kB > >
What happens when you disable sequential scans on pg10? regards -- Tomas Vondra http://www.2ndQuadrant.com PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services